The present invention relates to recording apparatus. More particularly, it relates to an operational control circuit for such a recording apparatus.
In the art relating to recording technology, there has been designed a recording medium which is sensitive to light signals to produce a latent image thereof. The latent image may then subsequently be developed by the application of controlled quantities of heat to the record medium. One type of such recording medium includes the optically sensitive emulsion on one side of a base carrier member, such as paper, with an electrically conductive backing member secured to the opposite side of the base carrier. The development heat for latent images in the emulsion is generated by the passage of electrical current through the conductive backing surface of the record medium by passing that record medium over two or more electrode members. In practice, at least one of the electrode members is resiliently biased to engage the surface of the record medium as it is drawn, under tension, between a pair of drive members. It has been found that if the record medium is not maintained taught between the drive rollers and is allowed to accumulate a bit of slackness therein, the heating electrodes do not maintain intimate contact with the conductive surface on the record medium and produce arcing. Such arcing at the electrodes not only causes poor development of the recorded image, shortened life of the electrodes and carbon deposit accumulations but it also constitutes a serious problem in that the continued arcing may cause the record medium itself to burn even after tension is restored.
There have been a number of efforts made to mechanically or electro-mechanically sense the tension in the record medium as it is drawn across such electrodes, none of these have been entirely satisfactory.